In Rust, if we returned and error (or a panic) during the client_connected reducer, the client will be disconnected.

Here is a simple example where the server module throws an error for all incoming client connections.

#[reducer(client_connected)]
pub fn client_connected(_ctx: &ReducerContext) -> Result<(), String> {
    let client_is_rejected = true;
    if client_is_rejected {
        Err("The client connection was rejected. With our current code logic, all clients will be rejected.".to_string())
    } else {
        Ok(())
    }
} 
    

Client behavior can vary by client type. For example:

• C# clients: Client disconnection behavior is currently undefined and will generate an error reading: Disconnected abnormally: System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake.

• Rust clients: Client disconnection behavior is currently undefined and will generate an error reading: Unable to send subscribe message: WS sender loop has dropped its recv channel: TrySendError { kind: Disconnected }

• TypeScript clients: Client will receive an Error connecting to SpacetimeDB: and a CloseEvent with a code of 1006.

Regardless of the client type, from the rust server's perspective, the client will be disconnected and the server module's logs will contain an entry reading: ERROR: : The client connection was rejected. With our current code logic, all clients will be rejected.

In C#, if we throw an exception during the ClientConnected reducer, the client will be disconnected.

Here is a simple example where the server module throws an error for all incoming client connections.

[Reducer(ReducerKind.ClientConnected)]
// Called when a client connects to a SpacetimeDB database server
public static void ClientConnected(ReducerContext ctx)
{
    throw new Exception("The client connection was rejected. With our current code logic, all clients will be rejected.");
} 
    

Client behavior can vary by client type. For example:

• C# clients: Client disconnection behavior is currently undefined and will generate an error reading: Disconnected abnormally: System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake.

• Rust clients: Client will receive an on_disconnected event with no error message.

• TypeScript clients: Client will receive an Error connecting to SpacetimeDB: and a CloseEvent with a code of 1006.

Regardless of the client type, from the C# server's perspective, the client will be disconnected and the server module's logs will contain an entry reading: ERROR: : System.Exception: The client connection was rejected. With our current code logic, all clients will be rejected.